Measurement of noise parameters of CW radar sensors

The CW radar sensors show no dead-zone and their output signal frequency is equal to the Doppler frequency. Owing to that, they can be used for many different purposes. Noise parameters of any radar sensor are decisive for its detection range, so their measurement is of the prime interest. The presented paper indicates all important sources of noise within the CW radar sensor and describes the method of measurement of its noise parameters. The noise sources include noise of linear and quasi-linear RF circuits, noise of LF circuits and noise contribution caused by the phase-noise of local oscillator. Since the latter noise source represents a strong function of the time-delay of signal cross-talked from the transmitter to the receiver, the developed measurement method is based on employment of the reflecting wall placed in front of sensor antennas or variable time-delay circuit connected within the receiver. Using the latter method enables the automatic measurement of noise parameters and, if required, full self-diagnostics of the radar sensor.